1. Field of the Invention
The present invention relates to a balloon catheter apparatus to be used in combination with a body cavity insertion device such as an endoscope or a laser probe.
2. Description of the Related Art
In a conventional technique, when, for example, the inside of the cavity of a vessel, such as a blood vessel, in which an opaque liquid flows is to be observed, the opaque liquid in the vessel cavity is replaced with a transparent liquid such as a physiological saline solution so as to ensure an observation field. Published Unexamined Japanese Utility Model Application No. 59-161119 discloses such a conventional technique.
In the above-described conventional technique, a liquid path is formed in the insertion portion of the endoscope, and a transparent liquid is flushed through the path to ensure a field of view. However, a blood flow cannot be blocked by simply flushing the transparent liquid from the distal end of the insertion portion. Hence, it is very difficult to keep a good field of view.
Published Unexamined Japanese Patent Application No. 61-293416, therefore, discloses a technique for blocking a blood flow from the upstream side in a blood vessel. In this conventional technique, a blood flow blocking balloon is arranged at the distal end of the insertion portion of an endoscope, and an inflation fluid source is connected to one end of a first tube which is inserted in the insertion portion. The other end of the first tube communicates with the inside of the balloon. A second tube is inserted in the insertion portion while one end of the tube is open to the distal end of the insertion portion and the other is connected to a transparent fluid source. A liquid is supplied from the inflation fluid source to the balloon to inflate it so as to block the blood flow from the upstream side. In this state, a transparent liquid is caused to flow from the transparent fluid source in order to ensure a field of view.
By blocking a blood flow with a balloon and replacing an opaque liquid with a transparent liquid in this manner, a good field of view can be ensured. In the above described conventional technique, however, the two tubes respectively used for supplying liquids from the inflation and transparent fluid sources must be inserted in the insertion portion. Therefore, the insertion portion is inevitably increased in size and cannot be suitably used especially for a narrow vessel such as a blood vessel. In addition, in order to ensure a good field of view, the inflation fluid source for inflating the balloon and the transparent fluid source for supplying a transparent liquid which are arranged at the proximal end of the insertion portion must be operated in a predetermined order. This complicates the operation. Moreover, an operation error tends to occur.